Length and girth weight calculation

[Javelin_Venom]

How exactly is this done and about how accurate do you think it is?

For example, if I have a largemouth bass that is 26" long and has a girth of 17 3/4"...how is this done?

[senile1]

If you're asking how to find the weight, I don't know the calculations behind it, but go to the top of this page and click on Tacklebox and then click Fish Weight Calculator and it will do it for you. I assume that some bass biologists have taken enough samples to have an accurate, scientifically valid survey of the weight associated with a particular length and girth. BTW, The length and girth you gave is approximately a 9.9 lb hawg.  Did you catch one with these dimensions?

[Javelin_Venom]

Yes, caught it at El Salto in Mexico this past week.  My new PB...not sure the exact weight...the guide that around 9 pounds...I thought AT LEAST 9 pounds.  Just wondering how close we were.  I will have pics to post soon.

[Glenn]

Use this: https://www.bassresource.com/bassfishing/fishcalculator.html

[langs15]

Nice fish!! Only a few inche son the girthand mine would bne close to yours..my PB(caught thhis year) was 22 in. 14 girth...and 6 pounds..

But on the calculater here sas it's 5.6...close enough I guess...

[Pa Angler]

Here's a site that weighs your fish with a ruler and it's pretty acurate.

www.dec.state.ny.us./website/dfwmr/fish/foe4cwgf.html

Chow

The Pa Angler

[langs15]

But the girth can drastically change the weight....

[cpvenom]

the most widely used formula is (length x lenght x girth)/ 1200.

helps to remember that when the 'net is not available

[Pa Angler]

Using my Berkley Digital scale, The weigh your fish with a ruler has always come within an once or two up here in PA and NY maybe it wouldn't hold up in the South where fish get bigger in the belly but up here it works.

Chow

The Pa Angler

[Pa Angler]

I tried the Bass Resource calculator and a length of 24" and a girth of 2" gave a weight of 3.9lbs, a length of 24" and a girth of 10" gave a weight of 3.9lbs, a length of 24" and a girth of 15" was 3.9lbs, a length of 24" and a girth of 17" was 3.9lbs and a length of 24" and a girth of 20" was you guessed it 3.9lbs something is wrong with this calculator and I did reset every time. It was for a Walleye.

Chow

The Pa Angler

[Guest the_muddy_man]

If shes stiin on two bar stools shes probablly too heavy

               

[Jerkbate]

I've stated before that I wouldn't completely trust the calculators.  I caught a fish earlier in the year that was 25" in length and 22" in girth.  The calculator said that it weighed 11.45 pounds.  However, someone posted a link to a fish that was registered with the share a lunker program in Texas that had a 25.5 in length and a 22 in girth that weighed over 15 pounds.  I know that the extra .5 inches in length will make a difference but a 4 pound difference is hard to believe.  

[Minuteman]

I used the BR calculator on Father's Day. I did a google search for "bass weight calculator" and the first hit was right here on BR. I knew we had the formula here, but I was unaware there was the automated calculator.

23"x16"= 7.05 Lbs. and a Father's Day Smile

[Matt Fly]

I always thought that the fish calculator was developed for Fla strains. Have read where the fish calculator is not as accurate on other strains of bass.

Rolo probably would have the info on this one.

another site

Largemouth bass vary not only in density, but also in their shape parameters. This is evidenced by the fat watermelon shaped fish caught in California versus the long, more slender fish caught in Florida. In order to accurately estimate the weight of a bass from these two different locations, two different models would have to be developed. The reason for this lies in the inherent fit parameters used in these models.

The article covers the formulas and why.

Most calculators seems to be in the ball park.

[George Welcome]

The caculator used in Florida by the biologists is complex and takes into account factors such as shape. But even so at best it is only an approximation. There is no way to account for mass or contents within the bass. Also, both the GFC in Florida, and Hal Schramm's caculations were based on a typical 10 pound bass: 27 X 17, with a variation in the weight of from 9 to 12 pounds. As per their caculations you can readily see the need for a scale. Measurement is critical and is difficult to do with accuracy. Buy a scale!

(The primary estimate is derived from a rather complex formula, which is what Commission biologists use. The equation is:)

Log (weight in grams)= -4.83 + 1.923 x Log (total length in millimeters) + 1.157 x Log (girth in millimeters).

[Tugfinder]

I still trying to figure out 31 long 26 girth.. this is the bass that I caught my biggest I'm wondering how much it weighs

[WRB]

On 6/25/2006 at 3:58 PM, Javelin_Venom said:

How exactly is this done and about how accurate do you think it is?

For example, if I have a largemouth bass that is 26" long and has a girth of 17 3/4"...how is this done?

26 x 26 x 17.5 = 11, 830 divide by 1200 = 9.86 lbs.

Your hypothetical is a skinny bass, the girth is rarely under 75% of the length.

Measuring is mouth closed laying flat from tip of jaw to center of tail. Girth is around the widest area with dorsal fin down.

L x L x G / 1200 = weight in pounds within 10%.

Tom 

22 hours ago, Tugfinder said:

I still trying to figure out 31 long 26 girth.. this is the bass that I caught my biggest I'm wondering how much it weighs

20.82 lbs. stretching the truth are we! 

Tom

[jbsoonerfan]

22 hours ago, Tugfinder said:

I still trying to figure out 31 long 26 girth.. this is the bass that I caught my biggest I'm wondering how much it weighs

15 years later, here we are. 

 

Close to the world record. I would have snapped a pic. LOL

 

I would just tell everyone you caught a world record anyway.

[soflabasser]

The best way to know how much a largemouth bass weighs is by weighing it on a accurate scale. After that you can use this formula for a close estimate of the weight of a largemouth bass;

Length X Length X Girth / 1200 = Estimated weight of bass in pounds

I find this formula to be accurate when I compare weighing the same bass and seeing the difference. There are other online bass weight formulas that overestimate the weight of a bass, I do not recommend those formulas.

[Fallser]

On 6/28/2006 at 2:29 AM, Pa Angler said:

I tried the Bass Resource calculator and a length of 24" and a girth of 2" gave a weight of 3.9lbs, a length of 24" and a girth of 10" gave a weight of 3.9lbs, a length of 24" and a girth of 15" was 3.9lbs, a length of 24" and a girth of 17" was 3.9lbs and a length of 24" and a girth of 20" was you guessed it 3.9lbs something is wrong with this calculator and I did reset every time. It was for a Walleye.

Chow

The Pa Angler

Actually, you're not far off with the weights.  A 24 inch walleye is usually around 4 lbs.  A 26 inch one between 5 and 6 lbs, when you get up to 30 inches you're talking about a 10 lb fish.  Difference is that a walleye is what I would call a narrow bodied fish, where bass are wide body.  The narrower girths are going to give you a lighter weight, than a similar length bass with a wider girth.  

[ironbjorn]

On 6/3/2022 at 8:06 PM, jbsoonerfan said:

15 years later, here we are. 

 

Close to the world record. I would have snapped a pic. LOL

 

I would just tell everyone you caught a world record anyway.

Years ago my ex wife caught a carp while I was at work. She sent me a photo of the fish and posted it on Facebook. She thought she caught a giant bass. I should have realized then that if she couldn't tell the difference between a carp and a bass that she wouldn't be able to tell the difference between her husband and his pool league teammate.

[J Francho]

Oh my goodness....

 

[Dwight Hottle]

The Florida Fish & Wildlife Conservation Commission has an online calculator that I have found to be very accurate. Here is the link. 

 

https://myfwc.com/fishing/freshwater/fishing-tips/bass-weight-calculator/  

 

@Javelin_Venom  your bass at 26x17.75 would weigh 10.13lbs.

[WRB]

The Perry bass using this calculator weighs 25.57 lbs, 32”L, 28” G. Formulas are only as good as the measurements and be within 10% do to body mass of individual bass. No accurate scale then formulas help to estimate weight.

Pinching the tail increases length but standard practice for tournament length measurement.

Thanks for sharing.

Tom

[WRB]

I will take credit for the L x L x G / 1200 formula because it was my formula. 

Back in the late 60’s I started to document DD bass weights. What I realized was the IGFA formula wasn’t accurate for fresh water bass. Body mass didn’t come close using Length, Girth squared divided by 800. Having measured over a hundred DD LMB and knew the weights within my Chatillon 25 lb scale the IGFA formula didn't come close.  

Being a engineer I came up with L x L x G / 1200 because it supported my data. 

Is this formula accurate...,no it’s good for estimation within 10% if the measurements are accurate ,but a lot closer then IGFA formula.

For What it’s worth I did submit my formula to BASS and it was published in BASS Times around 1980.